Performance of stiffened and unstiffened cold-formed channel members in axial compression

Cold-formed steel members are finding increasing acceptance in the construction markets as primary structural elements. Among the members most commonly used is the open channel member, which offers easy fabrication and connection. Channel members can be plain in simple applications, but if provided with flange or web stiffeners, their performance in terms of strength/weight and stiffness/weight ratios and resistance to local buckling improves. This paper attempts to cast light onto the behaviour of stiffened and unstiffened channel members in various conditions of use. After discussing the section properties and how they change with the use of stiffeners, the sectionʹs structural performance is assessed according to British Standard specifications, BS5950 (British Standards Institution BS5950—Structural use of steelwork in building, Part 5: Code of practice for design of cold-formed sections, BSI, 1999). The work involves a wide parametric study in which channel members with various aspect ratios, stiffenersʹ sizes and slenderness ratios are analysed. The results reveal how the members could be profiled to obtain the optimum performance in various applications, and for this reason, the results can be of significant value to future designs of cold-formed channel members.